Field Detail

• sqlName

  java.lang.String sqlName

  Name of SQL function

• K_IDENTITY_VAL

  static final int K_IDENTITY_VAL

  See Also:

  Constant Field Values

• K_CURRENT_ISOLATION

  static final int K_CURRENT_ISOLATION

  See Also:

  Constant Field Values

• K_CURRENT_SCHEMA

  static final int K_CURRENT_SCHEMA

  See Also:

  Constant Field Values

• K_USER

  static final int K_USER

  See Also:

  Constant Field Values

• K_CURRENT_USER

  static final int K_CURRENT_USER

  See Also:

  Constant Field Values

• K_SESSION_USER

  static final int K_SESSION_USER

  See Also:

  Constant Field Values

• K_SYSTEM_USER

  static final int K_SYSTEM_USER

  See Also:

  Constant Field Values

• K_CURRENT_ROLE

  static final int K_CURRENT_ROLE

  See Also:

  Constant Field Values

• kind

  final int kind

  This class is used to hold logically different objects for space efficiency. kind represents the logical object type. See also ValueNode.isSameNodeKind(org.apache.derby.impl.sql.compile.ValueNode).

• methodName

  private java.lang.String methodName

  Java method name

• methodType

  private java.lang.String methodType

  Return type of Java method.

Constructor Detail

• SpecialFunctionNode

  SpecialFunctionNode​(int kind,
                      ContextManager cm)

Method Detail

• bindExpression

  ValueNode bindExpression​(FromList fromList,
                           SubqueryList subqueryList,
                           java.util.List<AggregateNode> aggregates)
                    throws StandardException

  Binding this special function means setting the result DataTypeServices. In this case, the result type is based on the operation requested.

  Overrides:

  bindExpression in class ValueNode

  Parameters:

  fromList - The FROM list for the statement. This parameter is not used in this case.

  subqueryList - The subquery list being built as we find SubqueryNodes. Not used in this case.

  aggregates - The aggregate list being built as we find AggregateNodes. Not used in this case.

  Returns:

  The new top of the expression tree.

  Throws:

  StandardException - Thrown on error

• getOrderableVariantType

  protected int getOrderableVariantType()

  Return the variant type for the underlying expression. All supported special functions are QUERY_INVARIANT

  Overrides:

  getOrderableVariantType in class ValueNode

  Returns:

  The variant type for the underlying expression.

• generateExpression

  void generateExpression​(ExpressionClassBuilder acb,
                          MethodBuilder mb)
                   throws StandardException

  Generate an expression that returns a DataValueDescriptor and calls a method off the language connection or the activation.

  Overrides:

  generateExpression in class ValueNode

  Parameters:

  acb - The ExpressionClassBuilder for the class being built

  mb - The method the code to place the code

  Throws:

  StandardException - Thrown on error

• toString

  public java.lang.String toString()

  Description copied from class: ValueNode
  Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

  Overrides:

  toString in class ValueNode

  Returns:

  This object as a String

• isSameNodeKind

  boolean isSameNodeKind​(ValueNode o)

  Description copied from class: ValueNode
  Some node classes represent several logical node types (to reduce footprint), which we call kinds. This means that implementations of ValueNode.isEquivalent(org.apache.derby.impl.sql.compile.ValueNode) cannot always just use instanceof to check if the other node represents the same kind. Hence this method needs to be overridden by all node classes that represent several kinds. This default implementation does not look at kinds. It is only called from implementations of isEquivalent.

  Overrides:

  isSameNodeKind in class ValueNode

  Parameters:

  o - The other value node whose kind we want to compare with.

  Returns:

  true if this and o represent the same logical node type, i.e. kind.

• isEquivalent

  boolean isEquivalent​(ValueNode o)

  Description copied from class: ValueNode
  Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

  This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

  Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

  One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

  SELECT c1+c2 FROM t1 GROUP BY c1+c2

  In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

  • The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
  • If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
  • If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
  • When comparing SQL NULLs in this context, they are considered to be equivalent.
  • If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.

  Specified by:

  isEquivalent in class ValueNode

  Parameters:

  o - the node to compare this ValueNode against.

  Returns:

  true if the two nodes are equivalent, false otherwise.